Distribution Of Trees Research Articles

Presettlement Tree Distributions and Forest Types of Northeast Ohio, USA, Mapped With Species Distribution Models

ABSTRACTQuestionsEuropean colonization radically transformed the landscapes of eastern North America. Understanding this legacy is vital to managing current ecological communities. To do so requires spatially explicit information about presettlement vegetation. Here we test the ability of species distribution models, which have rarely been used with historical data like land survey records, to generate useful predictions of presettlement tree distributions. These models also allow us to assess pre‐disturbance vegetation‐environment relationships.LocationCuyahoga County, Ohio, USA.MethodsGeneralized linear models, generalized boosting models, random forests, and maximum entropy models related the distributions of 17 tree taxa to elevation, slope, aspect, and soil type, based on 4234 tree observations from circa‐1800 surveys. Cluster analysis defined forest types and created a prediction map of forest types using random forests.ResultsThis study generated high‐resolution predictions of presettlement tree distributions. Fagus grandifolia and Carya spp. were predicted to have found suitable habitat in over half the area. Elevation was by far the most important predictor, followed by slope. Many taxa were more likely to occur at higher elevations, corresponding to the Allegheny Plateau, while others followed river valleys. Broadly, 51% of the county was predicted to support forest types with Fagus grandifolia and/or Acer spp., and 48% of the county was predicted to support forest types with Quercus spp., Carya spp., and/or Castanea dentata.ConclusionsThis study demonstrates that species distribution modeling with historical data provides insights into presettlement vegetation and vegetation‐environment relationships. Our results reveal striking ecological patterns not apparent in today's landscape, such as the sharp difference in vegetation between the Central Lowland and Allegheny Plateau. The maps created here offer a historical perspective that can inform conservation, education, and further research.

Potential natural vegetation pattern based on major tree distribution modeling in the western Rif of Morocco

Potential natural vegetation pattern based on major tree distribution modeling in the western Rif of Morocco

Agroforestry Dynamics Among Different Landholding Farmers in Vrishabhavathi Basin, Karnataka

The agroforestry emerges as effective adaptation strategy to combat climate change and restrict urban expansion in semi-arid regions of India. The present study aims at understanding the spatial distribution of trees and agroforestry characteristics among small, medium and large landholding farmers around Vrishabhavathi river stretch in peri-urban region of Bangalore. A total of 34379 trees and 41 tree species was recorded in 679.2 ha area belonging to 100 farmers. The major proportion of trees (85 %), belonged to commercial plantation crops such as Areca nut and Coconut. The data indicated significant linear correlation between landholding category and tree density, suggesting that increase in number of trees with increase in land size. Analysis on girth class distribution across landholding indicated that concentration of smaller-sized trees in small and medium landholders, suggesting subsistence-oriented agroforestry practices. An intermediate agroforestry is largely practiced in all three landholding categories, where perennial commercial plantation is done along with food and fodder crops. The study provides insight on agroforestry for farmers, urban planners, agriculture and horticulture functionaries to foster sustainable practices in polluted urban fringe.

Особенности структуры черничных ельников Большого Соловецкого острова

The research has been carried out in the most typical and widespread plantations for Bolshoy Solovetsky Island – in blueberry spruce forests. Forest management materials and data obtained from sample plots have been used. In the latter, as well as in their buffer zones, the diameters and heights of 325 registered trees have been measured and samples have been taken to study the age structure of the stands. The presence of all forest-forming species of the island has been established in the composition of blueberry spruce forests. The average breed composition is reflected by the formula: 6S2B1P1As (6 spruce trees, 2 birch trees, 1 pine tree, and 1 aspen tree). The majority (76 %) of stands is of 0.6–0.7 density, but at the same time, low-density stands also make up a significant proportion – 21 %, and high-density stands are almost absent. According to archival data, there have been no clear-cuttings on the Solovetsky Islands, with the exception of individual cuttings in the 1920s and 1930s when the Solovetsky Special Purpose Camp existed there. All this, it would seem, has to contribute to the preservation of old trees. However, the average age of spruce stands is 155 years, and the oldest live up to 250 years. This age can be considered the limit for the conditions of the Solovetsky Archipelago. It has been shown that all the stands are of different ages with a different distribution of trees by age classes. There are blueberry spruce forests with a significant gap between tree generations, as well as with a cyclical appearance of the maximum number of trees in certain periods. The following types of age structure have been identified: absolutely uneven-age, stepwise unevenage and cyclically uneven-age. Spruce trees have been found to grow quite well in diameter, but growth in height is inhibited, resulting in the formation of highly tapering trunks. On average, the trees reach their maximum height of about 20 m with a diameter of 30–40 cm. The relative height averages 0.66 m/cm – this is 67 % of the indicator of the mainland spruce forests. It is inversely related to the diameter: the greater it is, the lower is the relative height.

HIPSTR: highest independent posterior subtree reconstruction in TreeAnnotator X.

In Bayesian phylogenetic and phylodynamic studies it is common to summarise the posterior distribution of trees with a time-calibrated consensus phylogeny. While the maximum clade credibility (MCC) tree is often used for this purpose, we here show that a novel consensus tree method - the highest independent posterior subtree reconstruction, or HIPSTR - contains consistently higher supported clades over MCC. We also provide faster computational routines for estimating both consensus trees in an updated version of TreeAnnotator X, an open-source software program that summarizes the information from a sample of trees and returns many helpful statistics such as individual clade credibilities contained in the consensus tree. HIPSTR and MCC reconstructions on two Ebola virus and two SARS-CoV-2 data sets show that HIPSTR yields consensus trees that consistently contain clades with higher support compared to MCC trees. The MCC trees regularly fail to include several clades with very high posterior probability (≥ 0.95) as well as a large number of clades with moderate to high posterior probability (≥ 0.50), whereas HIPSTR achieves near-perfect performance in this respect. HIPSTR also exhibits favorable computational performance over MCC in TreeAnnotator X. Comparison to the recently developed CCD0-MAP algorithm yielded mixed results, and requires more in-depth exploration in follow-up studies. TreeAnnotator X - which is part of the BEAST X (v10.5.0) software package - is available at https://github.com/beast-dev/beast-mcmc/releases .

The Evapotranspiration Characteristics and Evaporative Cooling Effects of Different Vegetation Types on an Intensive Green Roof: Dynamic Performance Under Different Weather Conditions

Previous research has demonstrated that the multiple environmental benefits of green roofs are primarily associated with their evaporative cooling effect. However, current studies on green roof evapotranspiration (ET) mainly focus on extensive green roofs, and the evaporative cooling effect of intensive green roofs is still unclear. Using the intensive green roof of AQUA City in Nanjing as a case study, this research employs the three-temperature (3T) model combined with high-resolution thermal infrared imagery obtained via an unmanned aerial vehicle (UAV) to estimate the ET of different vegetation types. The study aims to explore the spatiotemporal variations in surface temperature, evapotranspiration (ET) rate, and evaporative cooling rate for various vegetation types under typical seasonal (summer and winter) and weather conditions (sunny, cloudy, and rainy before and after rainy days). The results showed that: (1) the ET rates and evaporative cooling effects of different types of vegetation differed significantly, with shrubs having the fastest ET rates, followed by arbors, and grasslands having relatively low ET rates. (2) Solar radiation and air temperature are the most crucial meteorological parameters for inducing ET on green roofs. In this study, the evaporative cooling performance showed the patterns of summer > winter and sunny > cloudy > rainy days. (3) In the spatial distribution of tree and irrigation plant groups, some low-temperature diffusion phenomena to the adjacent small microenvironments were evident, while the diffusion effect in winter is smaller and mainly shows the opposite warming characteristics. This study offers a valuable reference for quantifying the ET and evaporative cooling effects of various vegetation types on intensive green roofs, facilitating the optimization of vegetation configuration and supporting sustainable urban development.

Design of risk-based surveillance to demonstrate absence of Phytophthora agathidicida in New Zealand kauri forests

Kauri forests are threatened by kauri dieback disease, caused by the microscopic soil-borne pathogen Phytophthora agathidicida (PA). Despite it being more than 15 years since the pathogen was discovered on the New Zealand mainland, there is still a paucity of information on the distribution of symptomatic trees and/or of the pathogen itself, which makes it challenging to understand where the infection foci are and how fast the pathogen is spreading. The considerable cost of surveillance for PA, as well as the risks associated with people walking between infected and non-infected sites, necessitates careful prioritisation of sites to be selected for surveillance. This task requires an understanding of which part of the landscape and how much of it needs to be surveyed to effectively detect the pathogen if present. We use information on the distribution of kauri trees with visible stress symptoms in the canopy to develop a baseline relative risk map depicting areas where PA is most likely to be present for three kauri forests in Northland, New Zealand. The relative risk map provides a simple, yet effective management tool to target trees for surveillance, monitoring, and protection. Using this insight, we demonstrate the application of a proof of absence statistical model to determine the surveillance effort required to be confident that if no PA is found during surveillance in selected priority sites, the pathogen can confidently be considered absent from these areas. Results from these analyses showed that many samples are needed to achieve 95% confidence in pathogen absence, but this varied between forests and sectors of each forest. However, these analyses are valuable to guide field efforts as well as to ensure realistic expectations among practitioners. The methods described here are applicable to many other pathogens affecting plants of cultural and/or ecological importance worldwide.

Design of an Autonomous Orchard Navigation System Based on Multi-Sensor Fusion

To address the limitations of traditional GNSS-based navigation systems in orchard environments, we propose a multi-sensor fusion-based autonomous navigation method for orchards. A crawler-type agricultural platform was used as a test vehicle, and an autonomous orchard navigation system was constructed using a 2D LiDAR, a dynamic electronic compass, and an encoder. The proposed system first filters LiDAR point cloud data and uses the DBSCAN–ratio–threshold method to process data and identify clusters of tree trunks. By matching the center coordinates of trunk clusters with a fruit tree distribution map, the platform’s positional measurements are determined. An extended Kalman filter fusion algorithm is then employed to obtain a posterior estimate of the platform’s position and pose. Experimental results demonstrate that in localization accuracy tests and navigation tests, the proposed system provides high navigation accuracy and robustness, making it suitable for autonomous walking operations in orchard environments.

Assessment of the Spatial Pattern of Small Termite Mounds and Trees in Altered Lands in Benin (West Africa)

ABSTRACTTermite restore plant diversity and soil on altered lands in West Africa with particular abundance of small mound made by Trinervitermes trinervitus, Trinervitermes geminatus, Cubitermes spp. or Microcerotermes spp. The particular abundance of small mounds on altered lands suggests the existence of underlying abiotic and biotic factors. This study investigated the spatial patterns of termite mounds on the altered lands and its relationship with tree distribution in order to sustain the ecological restoration of the altered lands. Thus, unmanned aerial vehicle (UAV) was used to collect images on three different altered land sites of 18 ha characterised with termite mounds. The images were ortho‐mosaicked with Pix4D Mapper software. Termite mounds and trees were digitalised on these images in ArcGIS software. The Ripley's pair correlation function using spatstat package was applied to assess the spatial pattern and association of mounds and trees. An aggregative pattern (g(r) > 1) was revealed in the spatial distribution of both termite mounds and trees across all sites. Furthermore, a positive clustered association between termite mounds and trees was noted at two study sites, likely due to the absence of human disturbance. Therefore, this interaction should be vital for assisted ecological restoration and can be factored into efforts to accelerate the restoration of soils and plants on degraded lands. The authors then recommend future research to explore the specific role this attractive relationship plays in ecosystem restoration.

Assessment of multidimensional diversity and conservation of threatened timber trees in China under climate change

Understanding spatial patterns of multidimensional diversity is crucial for effective conservation planning, especially in mountainous regions that are often biodiversity hotspots. This study focused on assessing the impact of climate change on the distribution of 110 threatened timber tree species in China, combining species distribution models and phylogenetic frameworks to quantify multidimensional diversity indices. The research aimed to evaluate the effectiveness of these indices in guiding the prioritization of protected areas and conservation strategies in the face of climate change. The findings revealed that Chinese protected areas are projected to experience a significant decline in their ability to protect the top 15 % hotspots for evolutionarily distinct and globally endangered (EDGE) species under future climate scenarios. This decline ranges from 17.11 % to 29.93 %, highlighting the urgent need for adaptive conservation strategies. Energy-related factors, particularly annual mean temperature and temperature annual range, were identified as key drivers of timber tree distribution patterns. Based on these results, the study advocate for the integration of multidimensional diversity indices into conservation priority evaluation frameworks and considering species' evolutionary history and vulnerability when determining regional biodiversity targets. This approach can help improve the effectiveness of conservation efforts in the face of ongoing climate change.

Elevation gradients and environmental variables shaping tree diversity and composition in Srivilliputhur Wildlife Sanctuary, Western Ghats

ABSTRACT Srivilliputhur Wildlife Sanctuary holds significant value being a part of Western Ghats, which remains unexplored in terms of vegetation. The current study is the first quantitative assessment of tree distribution along an elevation gradient combined with environmental variables. Sampling was conducted from December 2020 to April 2021 in six elevation zones (Z1 to Z6). A total of 135 plots of 20m × 20m size were established, and the stems were measured (>30 cm GBH). Across a 5.4 ha studied area, 2157 individuals representing 188 tree species and 48 families were documented. Tree density (348-473 ind. ha−1), basal area (21.71-36.59 m2 ha−1), and species richness (84-122) were highest at mid-elevations. One-way ANOVA result highlighted the significant influence of elevation on species richness (p < 0.05). Canonical Correspondence Analysis revealed a good correlation between environmental variables and elevation. Furthermore, beta diversity showed intermediate dissimilarity between zones, ranging from 0.30 to 0.61. Z1 and Z6 exhibited the most dissimilarity (60%). Our study revealed tree diversity was least at higher elevations, suggesting good evidence of elevation and environmental filtering in shaping the overall tree diversity. Besides, the scarcity of a few species showed a point of concern. Hence, the current study suggests the implementation of strategic conservation plans to conserve species diversity in this area.

Spatio-temporal trends in the frost regime reveal late frost exposure to white spruce (Picea glauca [Moench] Voss) persists in northeastern America

Abstract The characteristics of the frost regime (intensity, frequency, and timing) contribute to shaping tree species adaptations and distribution as well as ecosystem productivity and functions. However, climate change increases the variability in extreme events; therefore, the different characteristics of the frost regime may diverge under climate change. Using the BioSim 11 software, we simulated daily air temperature at 512 locations over northeastern North America between 1901–2021 to determine how the spatio-temporal trends in the frost regime varied over this complex landscape and if spatio-temporal trends in extreme climatic events such as frosts are stronger compared to changes in aggregated climate variables such as mean annual air temperature and growing degree-days. We also used an eco-physiological model to conduct a case study focussing on white spruce to determine if trees are currently more exposed to growing season frosts than they were in the past by modelling the timings of budburst using the thermal time model. Our results showed that, at 67% of locations (343 locations), the day of the year of the last frost in spring (minimum daily air temperature&lt;0 °C) occurred, on average, earlier by seven days during 2001–2021 compared to 1901–1920, whereas it occurred, on average, later by four days at 33% of locations (169 locations). The average temporal trends in frost occurrence were similar in magnitude to the average trends in aggregated climate variables; however, their variances were larger compared to the aggregated climate metrics, showing that the frost regime does not change uniformly throughout our study area. Our case study also revealed that white spruce remains exposed to late frosts of low and intermediate intensities (minimum daily air temperature &lt;0; &lt;−2 °C) compared to the past but exposure to high-intensity frosts (minimum daily air temperature &lt;−4 °C) is rare. Since extreme events such as late frosts diverge in their response to climate change compared to aggregated climate variables, the mean annual temperature is not sufficient to predict how climate change will impact ecosystems through frost regimes.

Spatiotemporal Distribution of Mercury in Tree Rings and Soils Within Forests Surrounding Coal-Fired Power Plants

The release of mercury (Hg) from coal-fired power plants (CPPs) into local ecosystems poses substantial environmental and health hazards. This study was conducted in Chungcheong-nam-do, South Korea, a region featuring over half of the country’s coal power facilities, to estimate the impacts of CPPs on Hg distribution in forest ecosystems. By analyzing Hg concentrations in pine tree rings and soil at 21 locations around CPPs and comparing them to control sites and industrial zones, we present a nuanced understanding of the effects of CPPs on Hg concentration. The analysis of Hg concentrations in tree rings showed a significant decrease in Hg levels as the distance from the power plants increased, suggesting that CPPs primarily influence Hg distribution in trees within a 25 km radius. In contrast, soil Hg concentrations did not exhibit a clear trend. This may reflect the limitations of this study in accounting for the physicochemical properties of the soil at each sampling site. Nevertheless, the Potential Ecological Risk Index for soil Hg contamination indicated a higher risk rating within a 1 km radius of the CPPs compared to other locations. Hg concentrations in tree rings have shown a steady decline since the 1970s, suggesting the positive effects of air pollution regulations. This also highlights the value of tree core samples as effective tools for monitoring historical Hg pollution. Furthermore, the higher historical concentrations of Hg in tree rings imply that trees may have acted as sinks for atmospheric Hg in the past.

Public Perception of Urban Green Spaces and its Tree Diversity in Delhi

The relationship between man and nature plays an important role in the everyday lives of human societies. Places like Delhi and its people face major challenges and issues of urbanisation affecting their health and well-being. Urban greens such as parks play a major role in bringing greenness into the lives of urban dwellers. Trees are seen as a major green component in the urban greens. This paper attempts to understand how public sees green spaces and their uses. Tree diversity index (The Shannon Index also known as Shannon Weiner Index, is a statistical index that measures diversity by estimating species richness and evenness.) canopy cover, and tree trunk diameter have been taken as indicators of greenness of park. Tree distribution at the species level is studied in one of the parks managed by Delhi Development Authority as ‘Landmark greens’. The park users’ perception is studied using an ethnographic method. Whereas the Shannon index is 2.2, which is a moderate value, 50 per cent of the visitors could only identify the popular species namely Neem, Banyan, Ashok, and Peepal. People are aware of the potential benefits of trees and plants or the role of green spaces in their overall well-being. Some of the visitors are the regular ones as they use the park with a purpose to heal from respiratory tract infection, obesity, diabetes, and palpitation, while there are 22 per cent visitors who found the park unsafe during certain instances.

Sweet cherry response in absorption and mobility of 10B applied to soil and flowers under two soil boron conditions

AbstractBackgroundBoron (B) is an essential micronutrient for plants, and B deficiency reduces fruit set in sweet cherry trees. Several studies showed the advantages of foliar and soil B applications in fruit trees, but there is little information on the distribution of B in the plant, becoming an important issue when nutritional corrections are needed.AimsThe study aims to determine B mobility and distribution in sweet cherry trees, applying 10B to the flowers and soil, at different timings and under two levels of soil B availability.MethodsTwo experiments were conducted with sweet cherry trees. In the two previous seasons, the plants were managed in two soil B availability conditions (deficient and adequate). The experiments consisted of the applications of 10B solution to the flowers and the soil at different timings and under both soil B conditions.ResultsHigher 10B absorption occurred when the 10B was applied to the soil at full bloom than when it was applied before leaf senescence. Boron was mobilized to all the tissues, but mainly to the leaves. Nevertheless, the fruit presented no differences in 10B excess for both application timings. Irrespective of soil B conditions, the 10B applied to the soil at full bloom was absorbed and mobilized to different tissues, that is, roots + rootstock + trunk (39%–44%) and stems + leaves (53%–55%), showing no differences between them. A lower percentage of B was located in the fruit, with 1% and 8% at soil B‐deficient and B‐adequate conditions, respectively. The highest percentage of the 10B applied to the flowers remained in the fruit (∼70%), and nearly 20% and 10% were mobilized to stems + leaves and roots + rootstock + trunk, respectively, independent of the soil B condition.ConclusionsBoron applied to soil at full bloom or before leaf senescence, under B‐deficient soil condition, is absorbed and mobilized to all the plant tissues, enhancing the B status in sweet cherry trees particularly when it is applied at full bloom. However, B soil application before leaf senescence would improve the availability of B (reserves) to the flowers in the following season. Boron applied to the flowers, at full bloom, remains in a high proportion in the fruit, becoming an effective complementary method to meet the fruit demands of the growing season, independent of the soil B conditions.

Analysis of Influencing Factors of Green View Index Based on Street View Segmentation

Abstract. The calculation of green view index in street view image has become an emerging choice for many researchers. This article proposes a PSAT-Net semantic segmentation model and specifically designs a pyramid pooling attention module. This module cleverly integrates channel and spatial information, implicitly implementing a three-dimensional attention mechanism, and significantly improving performance indicators. By performing detailed semantic segmentation on street view image, this article deeply analyzes the impact of different street view parameter configurations on green view index, and studies in detail how these parameters affect the visual perception of urban greening. The experiment found that: (1) The Green view index(GVI) of most sampling points decreases as the FOV increases. The increase in GVI is mainly affected by the crown width and pitch angle, and the high-value points of GVI are more easily affected. (2) Pitch angle usually causes a slight increase in GVI, which is mainly affected by the distribution of tall trees and low vegetation. Tall trees cause an increase in GVI, while low vegetation causes a decrease in GVI. Similarly, high value points of GVI are more likely to produce larger differences. (3) The Heading parameter has no obvious impact on the overall visual impact of GVI. The difference in independent sampling points comes from the angle between the lens acquisition direction and the road forward direction.These findings not only enrich the theoretical connotation of green view index research, but also provide valuable references for practical applications.

Seasonal changes in hydraulic functions of eight temperate tree species: divergent responses to freeze-thaw cycles in spring and autumn.

Freeze-thaw cycles (FTCs) are the major seasonal environment stress in the temperate and boreal forests, inducing hydraulic dysfunction and limiting tree growth and distribution. There are two types of FTCs in the field: FTCs with increasing temperature from winter to spring (spring FTCs); and FTCs with decreasing temperature from autumn to winter (autumn FTCs). While previous studies have evaluated the hydraulic function during the growing season, its seasonal changes and how it adapts to different types of FTCs remain unverified. To fill this knowledge gap, the eight tree species from three wood types (ring- and diffuse-porous, tracheid) were selected in a temperate forest undergoing seasonal FTCs. We measured the branch hydraulic traits in spring, summer, autumn, and early, middle and late winter. Ring-porous trees always showed low native hydraulic conductance (Kbranch), and high percentage loss of maximum Kbranch (PLCB) and water potential that loss of 50% maximum Kbranch (P50B) in non-growing seasons (except summer). Kbranch decreased, and PLCB and P50B increased in diffuse-porous trees after several spring FTCs. In tracheid trees, Kbranch decreased after spring FTCs while the P50B did not change. All sampled trees gradually recovered their hydraulic functions from spring to summer. Kbranch, PLCB and P50B of diffuse-porous and tracheid trees were relatively constant after autumn FTCs, indicating almost no effect of autumn FTCs on hydraulic functions. These results suggested that hydraulic functions of temperate trees showed significant seasonal changes, and spring FTCs induced more hydraulic damage (except ring-porous trees) than autumn FTCs, which should be determined by the number of FTCs and trees' vitality before FTCs. These findings advance our understanding of seasonal changes in hydraulic functions and how they cope with different types of FTC in temperate forests.

Unveiling urbanization effects on trees outside forests along the urban-rural gradient in megacity Bengaluru

Rapid urbanization has caused significant changes along the urban-rural gradient, leading to a variety of landscapes that are mainly shaped by human activities. This dynamic interplay also influences the distribution and characteristics of trees outside forests (TOF). Understanding the pattern of these trees will support informed decision-making in urban planning, in conservation strategies, and altogether in sustainable land management practices in the urban context. In this study, we employed a deep learning-based object detection model and high resolution satellite imagery to identify 1.3 million trees with bounding boxes within a 250 ​km2 research transect spanning the urban-rural gradient of Bengaluru, a megacity in Southern India. Additionally, we developed an allometric equation to estimate diameter at breast height (DBH) from the tree crown diameter (CD) derived from the detected bounding boxes. Our study focused on analyzing variations in tree density and tree size along this gradient. The findings revealed distinct patterns: the urban domain displayed larger tree crown diameters (mean: 8.87 ​m) and DBH (mean: 43.78 ​cm) but having relatively low tree density (32 trees per hectare). Furthermore, with increasing distance from the city center, tree density increased, while the mean tree crown diameter and mean tree basal area decreased, showing clear differences of tree density and size between the urban and rural domains in Bengaluru. This study offers an efficient methodology that helps generating instructive insights into the dynamics of TOF along the urban-rural gradient. This may inform urban planning and management strategies for enhancing green infrastructure and biodiversity conservation in rapidly urbanizing cities like Bengaluru.

Salinity regulates radial growth of Cynometra ramiflora L. in the Sundarbans mangrove ecosystem

The mangrove biome is threatened by global environmental changes (including sea level rise, SLR) and anthropogenic disturbances. In this context, understanding the growth dynamics of mangrove species is essential for designing effective management plans for critical mangrove ecosystems such as the Bangladesh Sundarbans. Therefore, this study aims to (1) identify the growth-ring boundaries and tested their periodicity (annual nature) in one of the ecologically important understory mangrove species, Cynometra ramiflora in the Bangladesh Sundarbans, (2) determine the influences of climate and river discharge on radial growth, and (3) examine the influence of habitat variables (e.g., regulators, resources and forest structure) on radial growth. The growth-ring boundaries of C. ramiflora were distinct on the polished wood discs and marked by a layer of flattened fibers mixed with parenchyma. The agreement between individual growth-ring series and chronology statistics enabled us to develop for the first time a 42-year-long chronology spanning from 1979 to 2021. The results indicate that growth rings are annual and could be used for age and growth rate estimations. Monsoonal and annual precipitation enhanced radial growth. Growth was also positively influenced by the amount of river discharge received prior to the onset of growth, particularly during the pre-monsoon. Generalized additive models (GAMs) revealed that among the habitat variables, salinity had a strong negative influence on radial growth of the studied species in the Sundarbans, while tree density and diameter heterogeneity (coefficient of variation, CoV of diameter at breast height) had positive influences. This study revealed that C. ramiflora growth is strongly dependent on soil salinity and highlighted the potential of this approach for improving the prediction of future tree growth and distribution in the face of projected global changes, in particular, SLR.

Street tree communities reflect socioeconomic inequalities and legacy effects of colonial planning in Nairobi, Kenya

Street trees provide ecological and social benefits that sustain urban life, yet their distribution frequently mirrors socioeconomic inequalities, meaning underprivileged social groups also have fewer trees. The distribution patterns of urban trees are least documented in the cities of rapidly evolving middle-income countries. We assessed whether street tree abundance, size, condition, diversity, and composition vary across census-derived socioeconomic strata in Nairobi, Kenya. We sampled 2047 trees across 12 neighborhoods, covering 24 km of street, then used linear regression to understand how socioeconomic strata relate to street tree characteristics. We found substantial disparities in tree abundance, with affluent areas harboring 91.5 % of the trees sampled. Low-income areas and informal settlements had comparably few trees. Mean diameter and condition did not vary across socioeconomic strata, but high-income, formerly European neighborhoods had a higher proportion of small trees, indicating a bias in recent urban greening investments further benefiting these areas. Species diversity followed a similar pattern of inequality. High-income neighborhoods had over 30 % higher species richness and diversity than low-income areas. Even so, lower income neighborhoods exhibited greater differences in street tree community composition, and a higher proportion of trees that bear edible fruit or are used in traditional medicine. Overall, our results reveal pronounced spatial inequality in the distribution of street trees in Nairobi, reflecting not only socioeconomic differences but the enduring legacies of colonial planning.